Add InternalAffairs/NodeFirstOrLastArgument cop

This cop checks for `node.arguments.first` and `node.arguments.last`,
and corrects them to `node.first_argument` and `node.last_argument`,
respectively.

Version 1.30 of `rubocop-ast` adds support for `first_argument` on block
nodes, and is therefore required for this cop not to produce false
positives for those node types.

changelog/change_require_rubocop_ast_version_1_30_or_greater.md

@@ -0,0 +1 @@
+* [#12305](https://github.com/rubocop/rubocop/pull/12305): Require `rubocop-ast` version 1.30 or greater. ([@sambostock][])

lib/rubocop/cop/bundler/gem_comment.rb

@@ -161,9 +161,9 @@ def contains_checked_options?(node)
         end
 
         def gem_options(node)
-          return [] unless node.arguments.last&.type == :hash
+          return [] unless node.last_argument&.type == :hash
 
-          node.arguments.last.keys.map(&:value)
+          node.last_argument.keys.map(&:value)
         end
       end
     end

lib/rubocop/cop/gemspec/deprecated_attribute_assignment.rb

@@ -43,7 +43,7 @@ class DeprecatedAttributeAssignment < Base
         def on_block(block_node)
           return unless gem_specification(block_node)
 
-          block_parameter = block_node.arguments.first.source
+          block_parameter = block_node.first_argument.source
 
           assignment = block_node.descendants.detect do |node|
             use_deprecated_attributes?(node, block_parameter)

lib/rubocop/cop/internal_affairs.rb

@@ -12,6 +12,7 @@
 require_relative 'internal_affairs/method_name_end_with'
 require_relative 'internal_affairs/method_name_equal'
 require_relative 'internal_affairs/node_destructuring'
+require_relative 'internal_affairs/node_first_or_last_argument'
 require_relative 'internal_affairs/node_matcher_directive'
 require_relative 'internal_affairs/node_type_predicate'
 require_relative 'internal_affairs/numblock_handler'

lib/rubocop/cop/internal_affairs/node_first_or_last_argument.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module InternalAffairs
+      # Checks for the use of `node.arguments.first` or `node.arguments.last` and
+      # suggests the use of `node.first_argument` or `node.last_argument` instead.
+      #
+      # @example
+      #   # bad
+      #   node.arguments.first
+      #   node.arguments[0]
+      #   node.arguments.last
+      #   node.arguments[-1]
+      #
+      #   # good
+      #   node.first_argument
+      #   node.last_argument
+      #
+      class NodeFirstOrLastArgument < Base
+        extend AutoCorrector
+        include RangeHelp
+
+        MSG = 'Use `#%<correct>s` instead of `#%<incorrect>s`.'
+        RESTRICT_ON_SEND = %i[arguments].freeze
+
+        # @!method arguments_first_or_last?(node)
+        def_node_matcher :arguments_first_or_last?, <<~PATTERN
+          {
+            (send (send !nil? :arguments) ${:first :last})
+            (send (send !nil? :arguments) :[] (int ${0 -1}))
+          }
+        PATTERN
+
+        def on_send(node)
+          arguments_first_or_last?(node.parent) do |end_or_index|
+            range = range_between(node.loc.selector.begin_pos, node.parent.source_range.end_pos)
+            correct = case end_or_index
+                      when :first, 0 then 'first_argument'
+                      when :last, -1 then 'last_argument'
+                      else raise "Unknown end_or_index: #{end_or_index}"
+                      end
+            message = format(MSG, correct: correct, incorrect: range.source)
+
+            add_offense(range, message: message) do |corrector|
+              corrector.replace(range, correct)
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/internal_affairs/node_matcher_directive.rb

@@ -40,7 +40,7 @@ def on_send(node)
           return if node.arguments.none?
           return unless valid_method_name?(node)
 
-          actual_name = node.arguments.first.value
+          actual_name = node.first_argument.value
           directives = method_directives(node)
           return too_many_directives(node) if directives.size > 1
 
@@ -53,7 +53,7 @@ def on_send(node)
         private
 
         def valid_method_name?(node)
-          node.arguments.first.str_type? || node.arguments.first.sym_type?
+          node.first_argument.str_type? || node.first_argument.sym_type?
         end
 
         def method_directives(node)

lib/rubocop/cop/layout/argument_alignment.rb

@@ -79,7 +79,7 @@ def flattened_arguments(node)
 
         def arguments_with_last_arg_pairs(node)
           items = node.arguments[0..-2]
-          last_arg = node.arguments.last
+          last_arg = node.last_argument
 
           if last_arg.hash_type? && !last_arg.braces?
             items += last_arg.pairs

lib/rubocop/cop/layout/first_parameter_indentation.rb

@@ -72,7 +72,7 @@ def check(def_node)
           return if ignored_node?(def_node)
 
           left_parenthesis = def_node.arguments.loc.begin
-          first_elem = def_node.arguments.first
+          first_elem = def_node.first_argument
           return unless first_elem
           return if same_line?(first_elem, left_parenthesis)
 

lib/rubocop/cop/layout/heredoc_argument_closing_parenthesis.rb

@@ -182,7 +182,7 @@ def fix_closing_parenthesis(node, corrector)
         end
 
         def add_correct_closing_paren(node, corrector)
-          corrector.insert_after(node.arguments.last, ')')
+          corrector.insert_after(node.last_argument, ')')
         end
 
         def remove_incorrect_closing_paren(node, corrector)
@@ -271,7 +271,7 @@ def fix_external_trailing_comma(node, corrector)
         def add_correct_external_trailing_comma(node, corrector)
           return unless external_trailing_comma?(node)
 
-          corrector.insert_after(node.arguments.last, ',')
+          corrector.insert_after(node.last_argument, ',')
         end
 
         def remove_incorrect_external_trailing_comma(node, corrector)

lib/rubocop/cop/lint/erb_new_arguments.rb

@@ -106,7 +106,7 @@ def on_send(node)
         private
 
         def autocorrect(corrector, node)
-          str_arg = node.arguments[0].source
+          str_arg = node.first_argument.source
 
           kwargs = build_kwargs(node)
           overridden_kwargs = override_by_legacy_args(kwargs, node)
@@ -121,11 +121,11 @@ def correct_arguments?(arguments)
         end
 
         def build_kwargs(node)
-          return [nil, nil] unless node.arguments.last.hash_type?
+          return [nil, nil] unless node.last_argument.hash_type?
 
           trim_mode_arg, eoutvar_arg = nil
 
-          node.arguments.last.pairs.each do |pair|
+          node.last_argument.pairs.each do |pair|
             case pair.key.source
             when 'trim_mode'
               trim_mode_arg = "trim_mode: #{pair.value.source}"

lib/rubocop/cop/lint/non_deterministic_require_order.rb

@@ -94,7 +94,7 @@ def on_block_pass(node)
           parent_node = node.parent
 
           add_offense(parent_node) do |corrector|
-            if parent_node.arguments.last&.block_pass_type?
+            if parent_node.last_argument&.block_pass_type?
               correct_block_pass(corrector, parent_node)
             else
               correct_block(corrector, parent_node)
@@ -116,7 +116,7 @@ def correct_block(corrector, node)
 
         def correct_block_pass(corrector, node)
           if unsorted_dir_glob_pass?(node)
-            block_arg = node.arguments.last
+            block_arg = node.last_argument
 
             corrector.remove(last_arg_range(node))
             corrector.insert_after(node, ".sort.each(#{block_arg.source})")
@@ -130,9 +130,7 @@ def correct_block_pass(corrector, node)
         # @return [Parser::Source::Range]
         #
         def last_arg_range(node)
-          node.arguments.last.source_range.with(
-            begin_pos: node.arguments[-2].source_range.end_pos
-          )
+          node.last_argument.source_range.with(begin_pos: node.arguments[-2].source_range.end_pos)
         end
 
         def unsorted_dir_loop?(node)

lib/rubocop/cop/lint/trailing_comma_in_attribute_declaration.rb

@@ -34,7 +34,7 @@ class TrailingCommaInAttributeDeclaration < Base
         MSG = 'Avoid leaving a trailing comma in attribute declarations.'
 
         def on_send(node)
-          return unless node.attribute_accessor? && node.arguments.last.def_type?
+          return unless node.attribute_accessor? && node.last_argument.def_type?
 
           trailing_comma = trailing_comma_range(node)
 

lib/rubocop/cop/mixin/check_line_breakable.rb

@@ -218,7 +218,7 @@ def process_args(args)
 
       # @api private
       def already_on_multiple_lines?(node)
-        return node.first_line != node.arguments.last.last_line if node.def_type?
+        return node.first_line != node.last_argument.last_line if node.def_type?
 
         !node.single_line?
       end

lib/rubocop/cop/naming/block_forwarding.rb

@@ -54,7 +54,7 @@ def self.autocorrect_incompatible_with
         def on_def(node)
           return if node.arguments.empty?
 
-          last_argument = node.arguments.last
+          last_argument = node.last_argument
           return if expected_block_forwarding_style?(node, last_argument)
 
           register_offense(last_argument, node)

lib/rubocop/cop/naming/memoized_instance_variable_name.rb

@@ -203,7 +203,7 @@ def on_or_asgn(node)
 
         # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
         def on_defined?(node)
-          arg = node.arguments.first
+          arg = node.first_argument
           return false unless arg.ivar_type?
 
           method_node, method_name = find_definition(node)

lib/rubocop/cop/style/access_modifier_declarations.rb

@@ -168,12 +168,12 @@ def message(range)
 
         def find_corresponding_def_node(node)
           if access_modifier_with_symbol?(node)
-            method_name = node.arguments.first.value
+            method_name = node.first_argument.value
             node.parent.each_child_node(:def).find do |child|
               child.method?(method_name)
             end
           else
-            node.arguments.first
+            node.first_argument
           end
         end
 

lib/rubocop/cop/style/accessor_grouping.rb

@@ -166,7 +166,7 @@ def separate_accessors(node)
               *processed_source.ast_with_comments[arg].map(&:text),
               "#{node.method_name} #{arg.source}"
             ]
-            if arg == node.arguments.first
+            if arg == node.first_argument
               lines
             else
               indent = ' ' * node.loc.column

lib/rubocop/cop/style/case_like_if.rb

@@ -125,7 +125,7 @@ def find_target_in_send_node(node)
           when :==, :eql?, :equal?
             find_target_in_equality_node(node)
           when :===
-            node.arguments.first
+            node.first_argument
           when :include?, :cover?
             find_target_in_include_or_cover_node(node)
           when :match, :match?, :=~
@@ -134,7 +134,7 @@ def find_target_in_send_node(node)
         end
 
         def find_target_in_equality_node(node)
-          argument = node.arguments.first
+          argument = node.first_argument
           receiver = node.receiver
           return unless argument && receiver
 
@@ -152,7 +152,7 @@ def find_target_in_include_or_cover_node(node)
         end
 
         def find_target_in_match_node(node)
-          argument = node.arguments.first
+          argument = node.first_argument
           receiver = node.receiver
           return unless receiver
 
@@ -185,7 +185,7 @@ def collect_conditions(node, target, conditions)
         def condition_from_send_node(node, target)
           case node.method_name
           when :is_a?
-            node.arguments.first if node.receiver == target
+            node.first_argument if node.receiver == target
           when :==, :eql?, :equal?
             condition_from_equality_node(node, target)
           when :=~, :match, :match?

lib/rubocop/cop/style/empty_literal.rb

@@ -83,7 +83,7 @@ def first_argument_unparenthesized?(node)
           parent = node.parent
           return false unless parent && %i[send super zsuper].include?(parent.type)
 
-          node.equal?(parent.arguments.first) && !parentheses?(node.parent)
+          node.equal?(parent.first_argument) && !parentheses?(node.parent)
         end
 
         def replacement_range(node)

lib/rubocop/cop/style/eval_with_location.rb

@@ -84,7 +84,7 @@ def on_send(node)
           # are considered.
           return if node.method?(:eval) && !valid_eval_receiver?(node.receiver)
 
-          code = node.arguments.first
+          code = node.first_argument
           return unless code && (code.str_type? || code.dstr_type?)
 
           check_location(node, code)
@@ -165,7 +165,7 @@ def check_file(node, file_node)
         end
 
         def check_line(node, code)
-          line_node = node.arguments.last
+          line_node = node.last_argument
           line_diff = line_difference(line_node, code)
           if line_diff.zero?
             add_offense_for_same_line(node, line_node)
@@ -227,7 +227,7 @@ def add_offense_for_missing_location(node, code)
         end
 
         def missing_line(node, code)
-          line_diff = line_difference(node.arguments.last, code)
+          line_diff = line_difference(node.last_argument, code)
           sign = line_diff.positive? ? :+ : :-
           expected_line(sign, line_diff)
         end

lib/rubocop/cop/style/explicit_block_argument.rb

@@ -86,7 +86,7 @@ def on_yield(node)
 
         def extract_block_name(def_node)
           if def_node.block_argument?
-            def_node.arguments.last.name
+            def_node.last_argument.name
           else
             'block'
           end
@@ -127,7 +127,7 @@ def call_like?(node)
         end
 
         def insert_argument(node, corrector, block_name)
-          last_arg = node.arguments.last
+          last_arg = node.last_argument
           arg_range = range_with_surrounding_comma(last_arg.source_range, :right)
           replacement = " &#{block_name}"
           replacement = ",#{replacement}" unless arg_range.source.end_with?(',')

lib/rubocop/cop/style/method_call_with_args_parentheses.rb

@@ -239,7 +239,7 @@ def args_end(node)
         def args_parenthesized?(node)
           return false unless node.arguments.one?
 
-          first_node = node.arguments.first
+          first_node = node.first_argument
           first_node.begin_type? && first_node.parenthesized_call?
         end
       end

lib/rubocop/cop/style/method_def_parentheses.rb

@@ -170,7 +170,7 @@ def anonymous_arguments?(node)
           return true if node.arguments.any? do |arg|
             arg.forward_arg_type? || arg.restarg_type? || arg.kwrestarg_type?
           end
-          return false unless (last_argument = node.arguments.last)
+          return false unless (last_argument = node.last_argument)
 
           last_argument.blockarg_type? && last_argument.name.nil?
         end

lib/rubocop/cop/style/redundant_argument.rb

@@ -67,7 +67,7 @@ def on_send(node)
           return unless redundant_argument?(node)
 
           offense_range = argument_range(node)
-          message = format(MSG, arg: node.arguments.first.source)
+          message = format(MSG, arg: node.first_argument.source)
 
           add_offense(offense_range, message: message) do |corrector|
             corrector.remove(offense_range)
@@ -80,7 +80,7 @@ def redundant_argument?(node)
           redundant_argument = redundant_arg_for_method(node.method_name.to_s)
           return false if redundant_argument.nil?
 
-          node.arguments.first == redundant_argument
+          node.first_argument == redundant_argument
         end
 
         def redundant_arg_for_method(method_name)

lib/rubocop/cop/style/redundant_sort.rb

@@ -180,7 +180,7 @@ def suffix(sorter)
         end
 
         def arg_node(node)
-          node.arguments.first
+          node.first_argument
         end
 
         def arg_value(node)

lib/rubocop/cop/style/select_by_regexp.rb

@@ -146,7 +146,7 @@ def find_regexp(node, block)
           return node.child_nodes.first if node.match_with_lvasgn_type?
 
           if node.receiver.lvar_type? &&
-             (block.numblock_type? || node.receiver.source == block.arguments.first.source)
+             (block.numblock_type? || node.receiver.source == block.first_argument.source)
             node.first_argument
           elsif node.first_argument.lvar_type?
             node.receiver